1. Field of the Invention
The present invention relates to door frames and, more particularly to a thermally insulated aluminum door frame.
2. Description of the Prior Art
There already exists some frame constructions for doors which are designed to avoid heat transfer between the inner and outer wall surfaces at the door opening. U.S. Pat. No. 3,141,205, issued on July 21, 1964 to Russell, discloses a jamb construction which can be installed for use with many different types of panels or walls. This jamb construction which is made from a plastic resilient material could provide such a thermal barrier by using, more specifically, an insulating resilient material. However, it is not shown how the door is hinged to the jamb construction while maintaining the thermal barrier.
In U.S. Pat. No. 3,037,589, issued on June 5, 1962 to Cole, the insulated frame comprises two metal ogee sections, one on each side of the wall, each including three flanges, one of which extends within the door opening. An insulated resilient connector strip is provided to join the two ogee sections within the door opening. The connector strip further provides bearings against which the door closes for sealing and shock absorbing purposes. Although this construction provides a thermal break, again, it is not shown how the door is hinged to the frame construction.
U.S. Pat. No. 4,344,254, issued on Aug. 17, 1982 to Varlonga, discloses a door frame provided with an uninterrupted heat insulating barrier disposed between two distinct metal sub-frames forming the fixed framework mounted to the wall. The construction disclosed in this Patent is rather complicated. As in the previous Patent, a conventional hinge could not be solidly secured to the frame construction as it would have to be mounted to tubular sections of the framework. For instance, if screws are used to fasten a leaf hinge to these patented jambs, these screws would then be engaged through a thin metal sheet of the jamb, with most of the threads thereof being thus useless as hanging in cavities of the tubular sections.